Converters for converting analog signals to digital signals and vice versa are found in a wide variety of circuits and devices, including compact disc (CD) players, digital video disc (DVD) players, signal processors, and various other systems that communicate signals. In general, the accuracy and quality of the signal conversion process increases with increasing sampling rate provided, that noise introduced by the digitization process (i.e., sampling and quantization) is properly taken into consideration.
Multi-stage noise shaping (MASH) converters are frequently used to separate and remove noise inherently introduced by digitization. Typically, as the number of noise-shaping stages of a MASH converter increases, the quality of the desired signal also increases. MASH converters are particularly useful for applications in which oversampling is used, such as in certain pulse-width-modulation (PWM) converters. The term oversampling refers to the use of sampling frequencies that exceed a frequency dictated by the Nyquist theorem in order to boost signal-to-noise ratio and reduce quantization noise.
Unfortunately, as the number of noise-shaping stages (i.e. the order of the MASH converter) increases, power consumption and surface area requirements also increase.